The present invention relates to light-measuring systems.
In particular, the present invention relates to systems of this type which are adapted to respond to the brightness of a given scene in order to achieve a given output corresponding to this brightness.
The features of the present invention are particularly adapted for use in photography. In connection with photography it is known that the film which is used is to be exposed to an object which is to be photographed within a particular density curve of the film taking into consideration the range of brightness of the object to be photographed, so as to achieve in this way a good tone in the photographic reproduction. Up to the present time, however, there has been no satisfactory light-measuring device which takes such a density curve into consideration. The reason for this is that such light measurement is difficult to provide and in addition certain photographers who are seriously concerned with light measuring of this type utilize conventional electrical exposure meters for partial measurement of the light of the object to be photographed so as to obtain in this way a photograph taking into consideration the density curve of the film and the brightness at the object to be photographed.
Conventional electrical exposure meters of this type have been developed from those employing selenium cells. These exposure meters have a wide viewing angle where the meter is exposed to the light at the object which is to be photographed. On the other hand, there are meters employing cadmium sulfide resistors which are exposed to light with a relatively narrow viewing angle. There has been a recent movement in the photographic industry to utilize so-called spot exposure meters particularly adapted for partial light measurement, and the result has been a rapid progress in light-measuring techniques.
While certain advances have indeed been made with measurement of light utilizing spot exposure meters with a narrow viewing angle, these types of devices have the disadvantage of requiring inconvenient manual operations as well as visual scanning through a viewfinder over the entire scene which is to be photographed, with the different parts of the scene being successively scanned so that light measurement is made of the different parts of the scene. Up to the present time there is no camera which utilizes a spot exposure meter of this type in such a way that such a meter is incorporated into the camera because of the inconveniences which would result in view of the fact that such a camera would require the operator to swing the camera over the scene in order to scan the scene which is to be photographed for the regions thereof which are of maximum and minimum brightness.